Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish that this is a read-only, idempotent, non-destructive, closed-world operation. The description adds useful context about return formats (PDF text, OCR marked as such, SIE) and names the API endpoint, but it does not disclose error behavior, permissions, or other operational details beyond that.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and mostly front-loaded, moving quickly from resource to returned text formats to API endpoint. The opening fragment 'The invoice as a PDF' is slightly misleading because the tool returns text rather than a PDF file, but there is little wasted text.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple read-only tool with full schema coverage, annotations covering safety, and an output schema, the description is largely complete for invocation. Its main missing piece is sibling differentiation among the many invoice/PDF/document reading tools.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the single DocumentNumber parameter is already documented as identifying the invoice. The description only references DocumentNumber through the endpoint path and does not add format or validation semantics beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the resource (invoice) and output (readable text from a PDF, OCR, or SIE), with the Fortnox preview endpoint. It is specific enough to understand the operation, but it does not explicitly distinguish this from sibling tools such as get_invoice_pdf or read_invoice_document.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the tool is for reading invoice content as text, but it gives no explicit when-to-use guidance, prerequisites, or alternatives. With many sibling read/PDF tools available, the lack of routing guidance is a clear gap.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.